Bugatti Veyron tuning glitch?
- Thread starter NixxxoN
- 43 comments
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i don't know if the Veyron's glitch exist or not because of my ignorance about the sciences in general and math to, but i read this trhead and so doing some proofs, the Veyron 16.4 '13 of the game does 416 kmh of max speed on ssx route ( consider the downhill,and oil change to)9.30 am realistic surface,soft sport tires,and not 460 how i read here, so i make a fully tuned version, and yes with low suspension settings the front steering become very slow or dosen't works well, because weight and the downforce plus the speed (i think) ,but if i try to move the power to the rear wheels like 10:90 and use an high suspensions setting and hard springs setting to , the car's steering works well , i do 3.54,6 of lap time with ss tires.(485 kmh top speed,nitro).
Probably they fixed the unrealistic's top speed of some cars, as we know, but the STOCK Veyron had never did 460 kmh , on my gt6.
No, they did not fix top speed issue. The reason why you get ~416km/h with your 'stock' Veyron is because there is another unrealistic issue in GT6 (not for all cars, but for some, including Veyron): gearbox ratios are too short. If you notice, when you do your max speed, rpms are at the redline, about ~7000rpm. The real Veyron doesn't do such high revs at the top speed. So if you adjust your gearbox (top speed slider) so that top speed would be at about ~6000rpm, then your stock Veyron will do ~440km/h or so. Which is, ofcourse, unrealistic.
try it.
I did not measure it, tbh...but I tested quite a few cars, and they all had unrealistic top speeds. So it is something global that affects cars, not something specific to one car. And my theory is that something with aerodinamic calculation is wrong. And if that is the case, then the offset (difference) won't be constant, because different cars have different aerodinamic properties / drag / coeficient so say reduced drag of 5%, for lamborghini won't be the same as for VW Golf or american muscle car. And the top speed 'advantage' will be different as well.
Also if its air drag calculation issue, then difference at 150mph and at 250mph will also be different
- 10,918
- Sweden
- eran0004
I'm actually testing it now, I'll post my findings when I have enough data
To create some kind of cliffhanger: So far I've found a very interesting thing about the way that speeds are being measured in the game, it does have some interesting consequences for 4WD cars... more on that later on.
I'm actually testing it now, I'll post my findings when I have enough data
To create some kind of cliffhanger: So far I've found a very interesting thing about the way that speeds are being measured in the game, it does have some interesting consequences for 4WD cars... more on that later on.
My findings from previous year (yes, we noticed this physics issue back in december 2013...):
- 0-200 km/h acceleration: more or less OK (compared with GT5 and real life)
- 200km/h+ acceleration: the difference starts to be noticable (compared to GT5 and real life)
So it's not only top speeds, but high speed acceleration is unrealistic as well. This, ofcourse, is logical, if you have more 'hidden power / less resistance' then both, acceleration and top speed will be different.
- Some cars run out of gears (no surprise, when you have such strong 'push', you quickly start bouncing of rev limiter in top gear). Imagine you take stock real life car and you add extra '250HP', without adjusting gearbox... So to see the full difference in max speed number, you need to add more gears (make them longer). Or leave them unchanged but then measure acceleration differences (e.g. between GT5 and GT6)
- Almost all street/sports/super cars are affected by this issue, if they are capable of doing high enough top speeds (300km/h + is good, for noticable difference). I haven't found a car which did not have this issue, but I didn't test all of them. I did not test race cars too, because how do you test them? No reference with real life (wings can be adjusted, etc.) But maybe it's possible to test them against GT5 same race car
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- 10,918
- Sweden
- eran0004
I don't think there's any hidden power involved, all you need to get faster acceleration and higher top speed is reduced drag, since drag is a force acting in the opposite direction. Adding more power or reducing the drag gives the same result.
What I'm doing is that I convert the torque to force, to measure the strength of the opposing forces (mainly drag, but also some friction). If you set the power limiter low enough you get a flat power curve, and from the power curve and the RPM you can get an accurate measure of the torque. Multiply the torque by the gear ratio and divide by wheel radius and you get the force that accelerates the car. When the car hits top speed, the opposing forces equals the force from the engine to the ground.
The wheel radius is unknown, but it can be calculated using the engine rpm, the gear ratio and the wheel speed: v/w, where v is the wheel speed in m/s (kph / 3.6) and w is the angular velocity of the wheel in radians/s. W can be obtained by: rpm/60/gear ratio*2pi.
This gave me the following radii for the rear wheel:
Alfa Romeo TZ3: 344.6 ± 0.7mm
Bugatti Veyron: 354.5 ± 0.9mm
Fiat 500f: 232.6 ± 1.9mm
Lotus 97T: 329.3 ± 1.1mm
The faster the speed, the higher the accuraccy, since the speed is measured in integers. 100 kph could be 100.0 kph or 100.9 kph, so that's why there's some uncertainties.
So now that I know the wheel radii, I can convert torque to force: Nm*Gear ratio/wheel radius (m).
At top speed:
Alfa Romeo TZ3 produced 1280.7 ± 1 Nm of torque at a gear ratio of 1.597
Bugatti Veyron produced 1255.3 ± 1 Nm at 1.5
Fiat 500f produced 35.8 ± 1.6 Nm at 3.238
Lotus 97T produced 432.3 ± 0.9 Nm at 3.302
Multiplied by the gear ratio and divided by wheel radius it gives the following forces in Newtons:
At top speed:
Alfa Romeo TZ3 produced 1280.7 ± 1 Nm of torque at a gear ratio of 1.597
Bugatti Veyron produced 1255.3 ± 1 Nm at 1.5
Fiat 500f produced 35.8 ± 1.6 Nm at 3.238
Lotus 97T produced 432.3 ± 0.9 Nm at 3.302
Multiplied by the gear ratio and divided by wheel radius it gives the following forces in Newtons:
Alfa Romeo TZ3: 5935,9 ± 16.9 Newtons @ 476 km/h
Bugatti Veyron: 5311.9 ± 17.1 Newtons @ 404 km/h (indicated front wheel speed)
Fiat 500f: 498,3 ± 26.5 Newtons @ 123 km/h
Lotus 97T: 4335,2 ± 22.8 Newtons @ 299 km/h
And since that force is cancelled out by an equal opposing force at top speed, we know that the opposing forces are exactly the same.
The next step is to calculate the drag coefficient and the drag area of the cars. The force of drag is equal to 1/2 * p * v^2 * C * A, where p is the density of air, where v is the air speed, where C is the drag coefficient of the body and A is the drag area of the body. Out of all of these parameters we only know one for sure, and that is the velocity. Well, we know it sort of for sure, because the game doesn't show the airspeed of the car, it shows the wheel speed.
For most cars, the wheel speed is the same as the air speed (or ground speed, but if we assume that there's no wind in the simulation we can also assume that ground speed = air speed).However, there is one important exception, as I have discovered while doing these tests, and that is 4WD cars. Usually, the wheel speed is given by the wheel (wheels?) that isn't powered and the reason for that is that a powered wheel experiences a little bit of slip and thus it would travel slightly faster than the road and indicate a speed that's higher than the actual speed of the car.
Edit: That is actually not the case. I measured the time it took to cover 5000 meter at 421 km/h (as indicated by the HUD) and the result was 421.5 km/h, with an uncertainty of 1 km/h. So it seems instead like it's the front wheel speed indicator that shows an incorrect wheel speed, because I also tested if the front wheels were braking by fitting CH tyres on the front (which should give less traction and a higher speed if the front wheels were braking) and the result was that the speed dropped. Conclusion: The front wheel speed isn't slower than the indicated speed of the car and thus the front wheel speed indicator is wrong.
In 4WD cars, all wheels are powered and as a result all wheels have a little bit of slip. This means that the speed readings of a 4WD car are less reliable than the speed readings of a 2WD car. When examining the data from the Bugatti Veyron, I found that the speed that is displayed on the HUD when you drive it, is the average of the wheel speeds of the front and the rear wheels.
In my example the HUD indicated 409 km/h, when the front wheel speed was 404 and the rear wheel speed was 414. Since there's no reason why the front wheels would be braking, we can assume that the ground speed was less than or equal to 404, which means that the HUD speed was off by at least 5 km/h. This was with RS tyres, so I can imagine that the accuraccy drops even more when you use tyres with less grip.
Alright, so to make a long post even longer: time to calculate the drag coefficient and drag area. We don't actually know the value for C, A and p, so the best we can do really is to calculate the volume of the CAp "cube" and then we can see if we find some data for the real cars and calculate their CAp value as well. We know the total magnitude of the opposing forces, but we don't know howmuch of it that is from drag and how much that is from other resistances, but if we assume that all of it is from drag (in reality, most of it will be, especially at high speeds) we can make an equation where we insert the force on the left and the calculation to the right, like this:
5935.9 = 1/2*p*v^2*C*A
We solve v^2, which is 17336.11
5935.9 = 1/2*p*17336.11*C*A
Multiply both sides by 2:
11871.8=p*17336.11*C*A
Divide by 17336.11:
0.685 = C*A*p
For most cars, the wheel speed is the same as the air speed (or ground speed, but if we assume that there's no wind in the simulation we can also assume that ground speed = air speed).
Edit: That is actually not the case. I measured the time it took to cover 5000 meter at 421 km/h (as indicated by the HUD) and the result was 421.5 km/h, with an uncertainty of 1 km/h. So it seems instead like it's the front wheel speed indicator that shows an incorrect wheel speed, because I also tested if the front wheels were braking by fitting CH tyres on the front (which should give less traction and a higher speed if the front wheels were braking) and the result was that the speed dropped. Conclusion: The front wheel speed isn't slower than the indicated speed of the car and thus the front wheel speed indicator is wrong.
In my example the HUD indicated 409 km/h, when the front wheel speed was 404 and the rear wheel speed was 414. Since there's no reason why the front wheels would be braking, we can assume that the ground speed was less than or equal to 404, which means that the HUD speed was off by at least 5 km/h. This was with RS tyres, so I can imagine that the accuraccy drops even more when you use tyres with less grip.
Alright, so to make a long post even longer: time to calculate the drag coefficient and drag area. We don't actually know the value for C, A and p, so the best we can do really is to calculate the volume of the CAp "cube" and then we can see if we find some data for the real cars and calculate their CAp value as well. We know the total magnitude of the opposing forces, but we don't know howmuch of it that is from drag and how much that is from other resistances, but if we assume that all of it is from drag (in reality, most of it will be, especially at high speeds) we can make an equation where we insert the force on the left and the calculation to the right, like this:
5935.9 = 1/2*p*v^2*C*A
We solve v^2, which is 17336.11
5935.9 = 1/2*p*17336.11*C*A
Multiply both sides by 2:
11871.8=p*17336.11*C*A
Divide by 17336.11:
0.685 = C*A*p
So here are my results:
Alfa Romeo TZ3: 0.685 ± 0.005 CAp
Bugatti Veyron: 0.823 ± 0.007 CAp
Fiat 500f: 0.854 ± 0.06 CAp
Lotus 97T: 1.257 ± 0.015 CAp
The higher the speed, the lower the uncertainty.
Now, all we need is to find some real world data of cars and start comparing their values.
Edit: There's a mistake here. The speedometer of the Veyron seems to be correct, instead it's the front wheel speed indicator that doesn't work properly.
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- 167
- Italy
- Vaira--80
agree that a game with 1200 cars can wrong stuffs o fa a lot of things,but this version of Veyron irl do 410kmh how i read in net,in game the no modificated version, no oil do 410 kmh , where is the error of max speed? ,speaking about rev glitch, max power for max rpm dosen't means that a car can't go over rev. However i like the passion that you use and that means we are always a fans of this game.
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You misunderstood me. There is no 'hiden power', but GT6 cars accelerate much faster than GT5 cars, although game specs say that both cars have the same engine power...so there is some 'force' which moves car faster OR there is less air resistance. So what you said is the same what I said
But what I wanted to emphasize is that in some tests you have to add longer gears or else the test data will be limited by gearbox setting not by engine power/air resistance calculation.BTW, I assume you are using Motec for data gathering, right?
Also, I remember that we tested somewhere wheel slip (with Motec), and GT6 accurately simulated wheel slip (spin) under high speed, and if you put softer tyres, you will get less wheel spin at high speed, than using harder or street tyres
agree that a game with 1200 cars can wrong stuffs o fa a lot of things,but this version of Veyron irl do 410kmh how i read in net,in game the no modificated version, no oil do 410 kmh , where is the error of max speed? ,speaking about rev glitch, max power for max rpm dosen't means that a car can't go over rev. However i like the passion that you use and that means we are always a fans of this game.
You can not look at one measure without looking at other things. Let me give you an example:
Lets say you take a stock car, 1000HP Bugatti Veyron, and it does 410 km/h.
Then you add 200HP engine tunning, and now it does 440 km/h
Then you take this 1200HP tuned Veyron and while going for top speed, you slightly apply brake. And it does 410 km/h max. The engine is producing more power but at the same time brake is adding more negative force and so both forces equal out and you have the same speed as with stock Veyron.
Does that mean that both, stock and tuned Veyrons have the same engine power, because they are doing the same top speed? (410km/h) ?
NO! Tuned Veyron has more HPs, but it has 'limiter' which prevents him from going faster.
So the same is with GT6 veyron, it would go faster (because of less air resistance bug in game) but it loses power after 6000rpm because of too short final gear ratio in game (not in real life).
Veyron engine power @ 6000rpm - 1000HP
Veyron engine power @ 7000rpm - 800HP
If you are doing top speed with stock GT6 Veyron, you are achieving 410km/h @ 800 hp. But at 1000hp you would achieve 440kph
Now you may ask, why the hell it's less power at 7000rpm? Well that is the way engines work. Look at engine power band: when engine revs rise, at first the power increases and then at certain point it reaches it's peak power, and then the power starts to drop and you lose a lot, very fast. So if the gearbox is set up wrongly, you'll get less top speed than you should.
And that is exactly what happens with Veyron in GT5 ! GT5 doesn't have air resistance bug. Would you like to know what is the top speed of stock Veyron, with stock gearbox, in GT5? 395 km/h !! Its too low. It should be 410!
But it also overrevs, at 7000rpm, so it also produces ~800hp and can't go faster than 395 395 + air resistance bug = 410 (GT6)
395 without bug = 395 (GT5)
see
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- 10,918
- Sweden
- eran0004
You misunderstood me. There is no 'hiden power', but GT6 cars accelerate much faster than GT5 cars, although game specs say that both cars have the same engine power...so there is some 'force' which moves car faster OR there is less air resistance. So what you said is the same what I said
BTW, I assume you are using Motec for data gathering, right?
Also, I remember that we tested somewhere wheel slip (with Motec), and GT6 accurately simulated wheel slip (spin) under high speed, and if you put softer tyres, you will get less wheel spin at high speed, than using harder or street tyres
I've made sure that I don't run out of gear in my tests
I use the data visualiser in the game, it's accurate enough for this purpose and it's also much faster than exporting and importing data from the PS3 to my PC.
You can not look at one measure without looking at other things. Let me give you an example:
Lets say you take a stock car, 1000HP Bugatti Veyron, and it does 410 km/h.
Then you add 200HP engine tunning, and now it does 440 km/h
Then you take this 1200HP tuned Veyron and while going for top speed, you slightly apply brake. And it does 410 km/h max. The engine is producing more power but at the same time brake is adding more negative force and so both forces equal out and you have the same speed as with stock Veyron.
Does that mean that both, stock and tuned Veyrons have the same engine power, because they are doing the same top speed? (410km/h) ?
NO! Tuned Veyron has more HPs, but it has 'limiter' which prevents him from going faster.
So the same is with GT6 veyron, it would go faster (because of less air resistance bug in game) but it loses power after 6000rpm because of too short final gear ratio in game (not in real life).
Veyron engine power @ 6000rpm - 1000HP
Veyron engine power @ 7000rpm - 800HP
If you are doing top speed with stock GT6 Veyron, you are achieving 410km/h @ 800 hp. But at 1000hp you would achieve 440kph
Now you may ask, why the hell it's less power at 7000rpm? Well that is the way engines work. Look at engine power band: when engine revs rise, at first the power increases and then at certain point it reaches it's peak power, and then the power starts to drop and you lose a lot, very fast. So if the gearbox is set up wrongly, you'll get less top speed than you should.
And that is exactly what happens with Veyron in GT5 ! GT5 doesn't have air resistance bug. Would you like to know what is the top speed of stock Veyron, with stock gearbox, in GT5? 395 km/h !! Its too low. It should be 410!
395 + air resistance bug = 410 (GT6)
395 without bug = 395 (GT5)
see
With the actual gear ratios of the real car I'm getting 421 km/h. To get 440 you need to set the gearbox to a taller ratio than what the real car have.
And I made a mistake by the way. I assumed that the speed indicator on the Bugatti Veyron didn't work because the front wheels and rear wheels were displaying different speeds and the front wheel speed was slower than the indicated speed. It turns out that it's in fact the front wheel speed indicator that doesn't work properly.
So now I need to recalculate my data for the Veyron
- 496
- Canada, Québec
- LET_QUEBEC_IN
To make the Veyron turn faster at high speed you need to raise the car because it dosn't have enough suspension travel at high speed when the wing goes lower. So what Gt should let us do, is decide when I want the wing to go lower or stay at his highest height during a race.
I've made sure that I don't run out of gear in my tests
I use the data visualiser in the game, it's accurate enough for this purpose and it's also much faster than exporting and importing data from the PS3 to my PC.
With the actual gear ratios of the real car I'm getting 421 km/h. To get 440 you need to set the gearbox to a taller ratio than what the real car have.
I got 432 km/h with stock GT6 Veyron and fixed ratios (top speed at ~6000rpm).
Real Veyron does top speed at ~6200rpm, and I did test for that, but I don't remember results now. I'll have to re-run test later and capture results.
BTW you can make 10 replays, save 10 files to USB at the same time, and load 10 files in your Motec Software on the PC. No need to go one by one.
